This invention relates to an optical communication apparatus, an optical communication information decoding method, an optical switching system and a driving method for an optical switching system and, more particularly, to an optical communication apparatus, an optical communication information decoding method, an optical switching system and a driving method for an optical switching system suitable for use for a switching process of multiplexed optical signals.
The field of optical communication has been developing rapidly together with the progress of the information-based society in recent years. In the field of optical communication, the progress is significant in the field of enhancement in function, beginning with the enhancement in transfer rate and the multiplexing of data.
As a multiplexing technique, wavelength multiplexing techniques, such as the WDM (Wavelength Division Multiplexing) and the DWDM (Dense Wavelength Division Multiplexing), have been developed.
In such a situation as described above, also with regard to a switching technique required for a repeating point of an optical fiber transmission line (hereinafter referred to merely as optical fiber), specifications for higher performances, such as a higher speed operation of an optical switch, are demanded.
More particularly, it is demanded to raise the speed of an optical switch, which quickly decodes header information included in information propagating in an optical fiber, that is, information in which a destination of information is recorded, and operates rapidly in response to the header information.
However, in the environment of the WDM or the DWDM, information propagating in an optical fiber and including header information cannot be read before optical wavelengths are demultiplexed from one another. Therefore, an optical switching system at a repeating point of an optical fiber cannot avoid having a configuration as shown in FIG. 1.
FIG. 1 shows an optical switching system which distributes and outputs wavelength-multiplexed optical signals inputted from an optical fiber 51 to optical fibers 52 and 53 in accordance with header information of the wavelength-multiplexed optical signals.
Referring to FIG. 1, wavelength-multiplexed light transmitted along the optical fiber 51 in accordance with the WDM or DWDM system is demultiplexed for individual wavelengths by a demultiplexer 54 and individually received by light reception units 55a to 55f. Information reading apparatus 56a to 56f read header information of information signals in the form of optical signals of the different wavelengths received by the light reception units 55a to 55f, respectively.
The information reading apparatuses 56a to 56f discriminate destinations of the individual information signals based on the header information to select output destinations of the information signals and signal the information signals to light emitting elements 57a to 57f or light emitting elements 58a to 58f. 
For example, if the information reading apparatus 56a discriminates that the output destination of the pertaining information signal is the optical fiber 52 side, then it outputs the information signal to the light emitting element 57a. On the other hand, if the information reading apparatus 56a discriminates that the information signal is the optical fiber 53 side, then it outputs the information signal to the light emitting element 58a. 
When each of the light emitting elements 57a to 57f and the light emitting elements 58a to 58f receives an information signal, it emits light of an optical signal of a predetermined wavelength corresponding to the information signal.
Optical signals of different wavelengths outputted from all or some of the light emitting elements 57a to 57f are multiplexed in accordance with the WDM or DWDM system by a multiplexer 59 and signaled to the optical fiber 52. On the other hand, optical signals of different wavelengths outputted from all or some of the light emitting elements 58a to 58f are multiplexed in accordance with the WDM or DWDM system by a multiplexer 60 and signaled to the optical fiber 53.
In this manner, at a repeating point of an optical fiber, a demultiplexer for demultiplexing wavelength-multiplexed light into different wavelengths used in the WDM or DWDM, light receiving elements for the individual wavelengths and a number of light emitting sources for the individual wavelengths equal to the number of fiber transmission lines used for transmission are required. Therefore, the optical switching system has a configuration of a great scale.
Further, since the optical switching system is configured such that it uses a procedure including demultiplexing of multiplexed wavelengths, light reception and information reading in order to select transmission destinations; it is limited to satisfaction of the demand for high speed optical switching.